Photographic emulsions containing chemical adjuvants dispersed in crystalloidal solvents

ABSTRACT

ORGANIC CRYSTALLOIDAL SOLVENTS OF THE FORMULA   R-COO-(CH(-X))N-CH(-Y)-N(-R&#39;&#39;)-R&#34;   WHEREIN R IS AN ALKYL RADICAL HAVING FROM 1 TO 18 CARBON ATOMS, N IS AN INTEGER UP TO 6, X AND Y INDIVIDUALLY ARE A HYDROGEN RADICAL OR AN ALKYL RADICAL, R&#39;&#39; IS A HYDROGEN ATOM, AN ALKYL GROUP OR THE MONOVALENT RADICAL   R-COO-(CH(-X))N-CH(-Y)-   WHERE R, X, Y AND N ARE AS DEFINED ABOVE; R&#34; IS A HYDROGEN ATOM OR ACYL RADICAL HAVING FROM 1 TO 18 CARBON ATOMS. THESE CRYSTALLOIDAL SOLVENTS ARE PARTICULARLY USEFUL IN DISPERSED COUPLER PHOTOGRAPHIC LAYERS AND CONSTRUCTIONS.

United States Patent Office 3,554,755 PHOTOGRAPHIC EMULSIONS CONTAINING CHEMICAL ADJUVANTS DISPERSED IN CRYSTALLOIDAL SOLVENTS Giancarlo Rinauro, Ferrania, Savona, Italy, assignor to Ferrania, S.p.A., Milan, Italy No Drawing. Filed Nov. 9, 1967, Ser. No. 681,921 Claims priority, application Italy, Sept. 15, 1967, 786,716/ 67 Int. Cl. G03c N US. Cl. 96-94 6 Claims ABSTRACT OF THE DISCLOSURE Organic crystalloidal solvents of the formula wherein R is an alkyl radical having from 1 to 18 carbon atoms, n is an integer up to 6, X and Y individually are a hydrogen radical or an alkyl radical, R is a hydrogen atom, an alkyl group or the monovalent radical where R, X, Y and n are as defined above; R" is a hydrogen atom or acyl radical having from 1 to 18 carbon atoms. These crystalloidal solvents are particularly useful in dispersed coupler photographic layers and constructions.

The present invention relates to novel classes of organic crystalloidal solvents, particularly suitable for use for introducing chemical adjuvants in photosensitive and even non-photosensitive layers of a silver halide photographic element, according to the dispersion method.

Various chemicals can be introduced by the method hereinabove set forth in the photographic materials. However, the adjuvants which most frequently are incorporated by this method in said materials are those compounds known as color formers or couplers that are introduced into the silver halide emulsions utilized in the preparation of photographic materials for color photography. It is known that in such photographic materials the colored images form by reaction of the color formers with the oxidation products of the color developer. A photographic material of this type usually comprises three layers superimposed one on another, each of which is sensitized to one of the three regions in which the visible spectrum is conventionally divided, namely yellow, magenta and cyan. Each layer contains at least a color former which, owing to the action of the oxidized developer, produces an image colored in one of those three colors.

For several reasons it is expedient that the chemical adjuvants to be added to the photosensitive emulsions and especially the couplers remain essentially immobile in the layer in which they are placed. In order to achieve this, the first effectual solution was to increase the molecular weight of the adjuvant that one desires to make non-diffusing, usually by the introduction of long saturated aliphatic chains (generally having 12-18 carbon atoms). This causes a decrease in the water solubility of the adjuvant. The problem was solved by introducing into the coupler molecule acidic functions capable of forming a salt, whereby the compound is made soluble in alkaline aqueous solutions, and then dissolving it in the hydrophilic colloid of the photographic emulsion.

Another method widely used is the so-called dispersion Patented Jan. 12, 1971 method. In this case one starts from couplers or other adjuvants having a predominantly lyophilic nature. Said couplers are then dissolved in a non-water miscible or only slightly miscible crystalloidal organic liquid having a high boiling point, a good solvent power and a good permeability to the developing agents. The solution of the coupler in said crystalloidal solvent is emulsified by means of a homogenizer with water with or without a. Water-permeable hydrophilic colloid of the type usually employed for producing photographic emulsions, and possibly, a surfactant. The dispersion obtained, formed by extremely small droplets of crystalloidal solvent containing the color former uniformly distributed in the water phase, may then be introduced into the photographic emulsion with no ditficulty.

In the present invention a class of compounds particu larly suitable for use as crystalloidal solvents for preparing dispersions of couplers and other chemical adjuvants has been found. The photographic materials which result therefrom exhibit excellent properties and, in the case of color materials, images having a definition higher than that provided by most of the known crystalloidal solvents are obtained. These crystalloidal solvents of the present invention are esters prepared from the condensation of linear or branched alkanolamines with fatty acids, the ester products having the general formula:

wherein R represents a linear or branched chain alkyl radical having from 1 to 18 carbon atoms; n is an integer up to 6, X and Y individually represent a hydrogen atom or an alkyl radical (preferably C to C R' represents hydrogen, alkyl or the monovalent radical:

wherein R, X, Y and n have the same meaning as above; and R" represents a hydrogen atom, or acyl having from 1 to 18 carbon atoms, either linear or branched chain.

These compounds are for the most liquid at room temperature, and those which are not liquid form liquid systems with the couplers at room temperature. They have a rather high boiling point (higher than 347.0" F. C.), at atmospheric pressure), and therefore during the drying subsequent to the coating of the photographic emulsion they do not evaporate. Moreover, they have a good light and heat stability as well as a good permeability to the oxidized products of the color developer. These solvents have also a solvent power higher than that of the crystalloidal solvents heretofore known, such as for example dibutyl phthalate, tricresyl phosphate, dibutyl lauramide, and like (see for example Italian Pat. No. 432,- 885), which permits a desirable reduction in the amount of crystalloidal solvent (e.g. from 30 to 50%) as compared to those solvents presently used.

One of the major disadvantages of the dispersed coupler system is derived from the presence in the photographic element of the crystalloidal solvent, which tends to adversely aifect the sensitization, increase the turbidity, and impair the adhesion of the layers. Since this invention permits the amount of said solvent to be noticeably reduced, it is obvious that such disadvantages are considerably minimized, if not completely eliminated. A further advantage associated with the lesser amount of solvent required is the reduced thickness of the layers, with resulting improvement of image definition. Moreover, it has been found that in the photographic materials containing solvents according to the present invention no formation of yellow fog in storage is observed.

Illustrative compounds suitable for use as crystalloidal solvents according to the present invention are listed in Table I. In the third column of the table the relative values of the solvent power of each material (expressed as milliliters of solvent required to bring into solution at a temperature of 158.0 F. (70 C.) are given) the standard for comparison being one gram of a conventional coupler having the formula By way of comparison Table I also reports the solvent power of three known crystalloidal solvents, identified as (a), (b), and (c).

Preparation of compound N0. 1: ethanolamine caprylate caprylamide Into a four-necked flask provided with stirrer, reflux condenser, dropping funnel and thermometer, 30.5 g. (0.5 mol) of ethanolamine were dissolved in 100 ml. of xylene; then 144 g. (1 mol) of caprylic acid were added rather quickly through the dropping funnel. During the 20 addition of the acid the temperature within the flask rose TAB LE 1 (1) Ethanolamine caprylate caprylamide C H;( CH2) 6C 0 0-0 H2CH2N HC O( C Hz) 5CH3 3. 5

(2) Propanolamine isobutyrate isobutyramide CH CH CH-COOCH2-CH2CHz-NHCOCH 2.7

C H; C H

(3) AIcthylcthanolamine butyrate butyramidc CH3 C.Hz-C Hz 0 O OCHz- C HZII I C O CI'Ir CH C H; 2, 3

(4) Etliyletllanolalnine butyratc butyramide CI-I CH -CHgC O OCH2CH2NC OCH2-CHZCH3 2. 5

(5) Uethyletlianolamine caprylate caprylamide CH3(CI*I' 1)5CO OCHg-CH -NC O(CHg) 5-011 2 6 (5) Ethylcthanolamine caprylate caprylamidc GIL-(CHM-C O OCHgCI-I2NC O(CH2)u-CH; 3

(7) Dicthanolamine dibutyrate butyramide C H -CH2CHg-C 0 0-0 Hz-CH2 2. 8

NC OCH2CHrCII C I{3CH2"C Hz-C O OCI-I: CH2

(8) Diotlianolalninc dicuprylatc caprylaiuidc ..CII (CII:)5-C O OCII;-CH2 2. 7

NC O(Cllflv-CII; CH (CH2)e-C O OCHz-CH (0) Diethauolalninc diacctate CHa-CO OCH2CH2 3.1

NII C1-I C O OCII' !C1I3/ (10) Dicthanolainine diacetate palmitoylamide C Hg-C O OCH2 C H; 2, 9

NC OCHT-CH N CH CO OCHr-CH C H; (11) Diisopropanolamine dibutyrate dibutyramidc C H CH2CH C O 0 CH C H NCOCHz-CH;CH 7

C II -CH2CII2C O OCI-IzCH C H (12) Diisopropanolamine dicaprylato eaprylamidc C H3 CH2) -0 0 OCH 311 3 NC O(CH2)0CH;

C I'I -(CII2)sC O O CIIflCl'1 (13) Ethanolpropnnolumine dibutyratc butyrann'de CH;(CHz-CH2-CO OCHzCHz-NC OCHz-ClIz-CII; 2. 7

CH3C1I2CII:C O OCHzCH 3H (a) Dlbutyl phtllulutu COOC41{9 0 1 At 2l2.0 F. (100 0.).

to l58.0 -176.0 F. (70-80 C.). As soon as the addition of the acid was completed, heating was started until a temperature of 320 F. (160 C.) was reached. This temperature was maintained for about 2 /2 hours. During this time the xylene distilled, carrying with it 17.5 ml. of reaction water (theory: 18 ml.). The reaction mixture was then allowed to cool down to room temperature, after which it was poured in a separatory funnel containing 400 ml. of diethyl ether and washed three times with 100 ml. of 10% HCl (each time), then three additional times with 100 ml. of water, then three times with 100 ml. of Na CO and finally three times with water until neutral. The ether solution was dried with g. of anhydrous Na SO for 24 hours, then was filtered on a folded filter in order to remove the sodium sulfate and finally was evaporated on a water bath. The residue was distilled under reduced pressure. The portion of overheads boiling below 212.0 F. (100 C.) was discarded, then the distillation was continued while further reducing the pressure. 137.5 g. of compound 1, a slightly strawyellow colored oil having a B.P. of 302.0 F. (150 C.)/1 mm. Hg, were recovered. Yield: 87%.

Preparation of compound No. 9: diethanolamine diacetate Into a 2000 ml. four-necked flask provided with stirrer, reflux condenser, dropping funnel and thermometer, 105 g. of diethanolamine were dissolved in 300 ml. of benzene. Then 120 g. of glacial acetic acid were slowly added through the dropping funnel. The reaction mixture was then allowed to boil for 4 hours. After that the benzene was distilled off, first at ordinary pressure and then at reduced pressure. Finally,, 148 g. of compound 9, having a B.P. of 359.6363.2 F. (l82184 C.)/l5 mm. Hg, were recovered. Yield: 78%.

Preparation of compound No. 10: diethanolamine diacetate palmitoylamide Into a 2000 ml. four-necked flask provided with stirrer, reflux condenser, dropping funnel and thermometer, and protected against moisture, 138 g. of compound 9 were dissolved in 600 of dry dioxane. Thereafter 131.2 g. of pyridine were added and then, still at room temperature, 200.4 g. of palmitoyl chloride were introduced through the dropping funnel. The mixture was allowed to boll for 4 hours, and the reaction mixture was then poured with stirring into 300 ml. of cold 5% HCLThe precipitate was filtered off and washed with water until neutral and was finally dried under vacuum. 202 g. of a material having a M.P. of 129.2138.2 F. (5459 C.) were recovered. After crystallization from 300 ml. of acetonitrile, 175 g. of compound 10, having a M.P. of -134.6- 138.2 F. (57-59 C.), were obtained. Yield: 70%.

Preparation of compound No. 13: ethanolpropanolamine dibutyrate butyramide Into a four-necked flask provided with stirrer, reflux condenser, dropping funnel and thermometer, 29.8 g. of ethanolpropanolamine were dissolved in 100 ml. of xylene. Thereafter, 66 g. of butyric acid were added, and the mixture was heated to 284.0302.0 F. (140150 C.). After one hour, distillation of xylene and water was initiated. After 4 hours of distillation ml. of xylene 7 5 and 10.5 ml. (theory: 13.5 ml.) of water of reaction were collected. Thereafter, the reaction mixture was allowed to cool down to room temperature and 300 ml. of diethyl ether were added. It was then washed three times in a separatory funnel with m1. of 10% HCl, thereafter three times with 100 ml. of water, then three times with 100 ml. of 5% Na CO and finally again with water until neutral. The ether solution was dried with 10 g. of dry Na SO for 24 hours, then was filtered on a folded filter to remove the sodium sulfate and finally was evaporated on a Water bath. The residue was distilled under reduced. pressure. The portion of overheads boiling below 212.0 F. (100 C.) was discarded then the distillation was continued while further reducing the pressure. 50 g. of compound 13 having a B.P. of 392.0393.8 F. (200- 201 C.)/1 mm. Hg, were recovered. Yield: 62%.

The compounds 3, 4, 5, 6, 7, 8, l1 and 12 in Table I were prepared in a similar manner.

The dispersions are prepared according to known techniques in a homogenizer, colloid mill or other similar apparatus, with or without the addition of emulsifiers. Sometimes it may be expedient to prepare the dispersion by adding a low boiling auxiliary solvent such as ethyl acetate, butyl acetate and like, into water or into a water solution of a naturally occurring or synthetic, waterpermeable, hydrophilic colloid, such as gelatin, polyvinyl alcohol, agar-agar, etc. In many cases it can be advantageous to use mixtures of two or more solvents in order to obtain dispersions having the desired photographic properties. For example, together with one of the crystalloidal solvents of the present invention, another solvent which is capable of changing the refractive index or other physical properties of the dispersion may be used.

It is important for the purposes of this technique that the coupler-solvent mixture is liquid at ambient or room temperature. The mixture forms, by dispersion in water or in a hydrophilic colloid, extremely small droplets which contain the coupler enclosed therein. These dispersions are quite stable, and they are permeable to the photographic processing baths. The photographic emulsions in which said dispersions of couplers or other chemical adjuvants can be introduced are the usual gelatinsilver halide emulsions, however, as stated hereinabove, the protective colloid can be wholly or partly replaced by other natural or synthetic hydrophilic colloids, such as polyvinyl alcohol, agar-agar, and like.

In order to better illustrate the present invention some examples of preparation of dispersions of chemical adjuvants to be introduced in the photographic emulsions are given herein-below.

EXAMPLE 1 1 gram of the coupler Was dissolved in 2 ml. of the compound No. 7 (see Table I), by heating at 212.0 F. (100 C.). The hot solution was poured into 20 ml. of a 4% gelatin solution containing 2 ml. of 10% sodium tetradecyl sulfate. The mixture was emulsified in a homogenizer, then introduced into a silver halide emulsion. This emulsion was then coated onto a suitable support and dried. The material thus prepared was exposed and then subjected to the usual color development bleaching and fixing processing steps. A magenta image having a good definition and no fogging was thus obtained.

EXAMPLE 2 1 gram of the coupler was dissolved in 2 ml. of the compound No. 5 of Table I by heating at 2l2.0 F. (100 C.). The hot solution was poured into 20 ml. of 4% gelatin containing 2 ml. of sodium tetradecyl sulfate. The mixture was emulsified in a homogenizer and was introduced into the silver halide emulsion. After coating the emulsion containing the dispersion onto a support, drying, exposure, color development and subsequent bleaching and fixing a magentacolored image was obtained.

EXAMPLE 3 1 gram of the coupler was dissolved by heating at 158.0F. (70 C.) in 0.5 ml. of the compound No. 8 of Table I in 4 ml. of ethyl acetate. The solution was poured into ml. of 4% gelatin containing 2 ml. of 10% sodium tetradecyl sulfate. The mixture was emulsified in a homogenizer and was introduced into the silver halide emulsion. After coating the emulsion containing the dispersion onto a support, drying, exposure, color development and subsequent bleaching and fixing, a magenta-colored image was obtained.

EXAMPLE 4 1 gram of the coupler 8 EXAMPLE 5 I gram of the ultraviolet obsorber 2-phenylamino-3- tetradecyl-5-benzal-4-thiazolidone of the formula was dissolved in 0.2 ml. of compound No. 10 in Table I by heating at l22.0 F. C.) with 2 ml. of ethyl acetate. The solution was poured into 20 ml. of 4% gelatin containing 2 ml. of 10% sodium tetradecyl sulfate. The mixture was emulsified in a homogenizer and was ready to be introduced into a silver halide emulsion or into another photographic emulsion layer.

EXAMPLE 6 I gram of the ultraviolet absorber (i)C H was dissolved in .02 ml. of compound No. 10 of Table I by heating at 122.0 F. (50 C.) with 2 ml. of ethyl acetate. The solution was poured into 20 ml. of 4% gelatin containing 2 ml. of 10% sodium tetradecyl sulfate. The mixture was emulsified in a homogenizer and was ready to be introduced into a silver halide emulsion or into another photographic layer.

The embodiments of the invention in which an exelusive property or privilege is claimed are defined as follows:

1. A photographic emulsion including a water-permeable hydrophilic colloid and having uniformly distributed therein a dispersion of a crystalloidal solvent containing at least one chemical adjuvant, said solvent being characterized by the formula 0 RI! ll R O (C 'I)n CIIN l I X Y R wherein R is an alkyl radical having l-18 carbon atoms, 11 is an integer of from 1 to 6, X and Y individually represent a hydrogen atom or a C -C alkyl group, R" is a hydrogen atom or an alkyl carbonyl group, having 1-18 carbon atoms, and R is a hydrogen atom, an alkyl group, or the monovalent radical wherein R, X, Y and n are as defined above.

2. A photographic element having at least one layer comprising a photographic emulsion of claim 1.

3. The photographic emulsion of claim 1 in which the chemical adjuvant is a color coupler.

4. The photographic emulsion of claim 1 in which the chemical adjuvant is an ultraviolet absorber.

5. The photogfiraphic emulsion of claim 1 in which the photographic emulsion is a silver halide containing emulsion.

6. The photographic emulsion of claim 5 in which the photographic emulsion is a silver halide gelatin emulsion.

(References on following page) References Cited 591,688 2/1960 can a a 96-94 UNITED STATES PATENTS 1,425,126 3/1967' France 96-94 12/1939 Jennings at 96100X WILLIAM D. MARTIN, Primary Examiner 33: 2:3 5 M. R. P. PARRONE, JR., Assistant Examiner FOREIGN PATENTS US. Cl. X.R. 10/1962 Great Britain 96-94 9 .400, 114 7, 115; 2 0 404 8/1965 Great Britain 96-94 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated Januarx 12, 1971 Giancarlo Rinauro Patent No.

Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 10, @0

should read --C I-I Column 8, line 30, ".02 ml. should read 0.2 ml.

Column 8, line 69, claim 5, "photogfiraphic" should read photographic Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD 'M.FLETCHER,JR. ROBERT GOT'ISCHALK Commissioner of Pate Attesting Officer 

